9.1.2 Number Literals

Number literals include exact-value (integer and
DECIMAL) literals and
approximate-value (floating-point) literals.

Integers are represented as a sequence of digits. Numbers may
include . as a decimal separator. Numbers may
be preceded by - or + to
indicate a negative or positive value, respectively. Numbers
represented in scientific notation with a mantissa and exponent
are approximate-value numbers.

Exact-value numeric literals have an integer part or fractional
part, or both. They may be signed. Examples:
1, .2,
3.4, -5,
-6.78, +9.10.

Approximate-value numeric literals are represented in scientific
notation with a mantissa and exponent. Either or both parts may
be signed. Examples: 1.2E3,
1.2E-3, -1.2E3,
-1.2E-3.

Two numbers that look similar may be treated differently. For
example, 2.34 is an exact-value (fixed-point)
number, whereas 2.34E0 is an
approximate-value (floating-point) number.